Effects Of Applying Quicklime And Tri-salt Nutrient Solution On Physiological And Ecological Characteristics Of Cryptomeria Fortunei Seedlings

Cryptomeria fortunei belongs to the genus Cryptomeriaceae in the family Cedaraceae.It is one of the rare species in Tianmushan National Nature Reserve,and has important scientific research value and ecological significance.In recent years,a large-scale decline of the Cryptomeria fortunei population in Tianmu Mountain has appeared.In order to restore the health of Cryptomeria fortunei population,the annual seedling of Cryptomeria fortunei in Tianmu Mountain was used in this study to evaluate the effects of different quicklimes(5g·plant^-1,10g·plant^-1,20g·plant^-1)and tri-salt nutrient solution(2g·plant^-1,4g·plant^-1,8g·plant^-1)on its growth and photosynthetic characteristics.The optimal rejuvenation scheme was found to provide scientific basis for the prevention and control of the decline of Cryptomeria fortunei population in Tianmu Mountain.The main results are as follows:（1）Quicklime promotes the growth of seedling height of Cryptomeria fortunei seedlings,but the growth of seedling diameter is not sensitive to quicklime response.In terms of photosynthetic characteristics,as the amount of quicklime increased,the net photosynthetic rate（Pn）of the leaves of Cryptomeria fortunei seedlings increased significantly,and the stomatal conductance（Gs）and intercellular carbon dioxide concentration（Ci）increased first and then decreased.The change of transpiration rate（Tr）is not obvious.As for chlorophyll fluorescence,quicklime significantly improves the maximum photochemical efficiency（Fv/Fm）and actual photosynthetic quantum yield（Y（Ⅱ））of the seedling leaves,and has no significant effect on the relative chlorophyll content（SPAD）of the leaves,rather than photochemical desorption（q N）decreased significantly.Under the treatment of different amounts of quicklime,the treatment with 20g·plant^-1 is the best,10g·plant^-1 is the second,and 5g·plant^-1 is the weakest.（2）The tri-salt nutrient solution also promoted the growth of seedling height and ground diameter of Cryptomeria fortunei seedlings.With the increase of tri-salt nutrient solution,the photosynthetic gas exchange parameters Pn,Gs,Ci,Tr of the leaves of Cryptomeria fortunei seedlings increased significantly,and showed a trend of first increasing and then decreasing.Seedling leaves of Fv/Fm and Y（Ⅱ）were similar to Pn andthe tri-salt nutrient solution on relative chlorophyll content（SPAD）of the leaves had no significant effect.,Neverthless,q N was significantly affected,showing a change of first decreasing and then increasing.Under the treatment of different amounts of tri-salt nutrient solution,the treatment with 4g·plant^-1 is the best,8g·plant^-1 is the second,and the effect of 2g·plant^-1 is the weakest.（3）Under different seasons,there is no difference in applying quicklime to Cryptomeria fortunei seedlings,and the application of tri-salt nutrient solution has obvious changes.The effect of 4g·plant^-1 in spring is the best,and the effect of 8g·plant^-1 in autumn is better.（4）Under different treatments,the three-salt nutrient solution treatment has a better effect than the quicklime treatment,and it improves the growth and photosynthetic characteristics of Cryptomeria fortunei seedlings more significantly.In summary,the appropriate amount of lime and tri-salt nutrient solution can effectively promote the growth and photosynthetic characteristics of Cryptomeria fortunei seedlings,but the tri-salt nutrient solution needs to be within a reasonable concentration range,too large or too small will cause nutrient imbalance.